Coating mixture



Patented June 27, 1933 UNITED STATES PATENT OFFICE I Drawing.hpplieation filed December This invention relates to the coating ofmetallic sheets or breakdowns for the purpose of preventing adhesion ofsuperposed sheets during the process of pack rolling, by

which the sheets are'elongated until they have the desired. thickness.The invention is also in'the nature of an improvement upon thecompositions and processes disclosed in my rior, copending application,Serial Num r 576,224, filed November 19, 1931.

Heretofore, various attempts have been made to provide a satisfactorycoating for the abuttingfaces of the sheets of a pack to be rolled forthe purpose of preventing adhesion of the sheets when heated and rolled.Such abutting faces, heretofore, have been coated with various compoundswhich, to some extent, resisted adhesion of the sheets to one another,but difliculty was experienced in 29 preventing such adhesion of thesheets and,

' at the same time, obtaining sheets of desired quality after rollingsuch as sheets which are clean, stainless, white in appearance, and havea close grained and high, glossy surface or finish.

An object of this invention is to provide an improved coating mixturefor, and method of, treating the metal sheets of packs for pack rolling,by which adhesion of the sheets to one another during rolling will beeflectively prevented; with which sheets may be fobtained that, afterrolling, will be superior ,in'appearance and quality to those heretoforeobtained; which will give dependable and uniform results; and which willbe relatively simple and inexpensive.

I have now discovered that superior results in pack rolling may beobtained by the use 40 of my improved coating composition which isapplied to the sheets of the pack before the sheets are heated androlled. In accordance with my discovery, I prepare the coating mixtureof finely divided carbon in a plu- A 5 rality of different, chemicallyuncombined forms that are mixed into and carried by a liquid suspendingmedium. When this mixture is applied to the faces of the sheets, itforms an adherent coating that protects the 6 faces of the sheets duringthe heating and manta :I. swore, or BLASDELL, NEW YORK I comma mxrunn e,1922. Serial no. 645,950.

' rolling operations,'and produces an improved finish on the faces ofthe sheets. Preferably, one of these chemically, uncombined forms ofcarbon to be used is graphite, and the amorphous and crystalline formsthereof are the most satisfactory. While the flaky graphite may be used,I have found it less satisfactory than the amorphous. or crystallineforms of the graphite. The other forms of the chemically, uncombinedcarbon in finely divided condition ma be finely divided charcoal andlampblac or other soot. The liquid suspension medium is preferably anaqueous solution of a sugar, such as molasses or glucose, and I havefound that glucose gives better results than the molasses or othersugars in that there is less discoloration of the sheets with the use ofthe glucose. The sugar or glucose. acts as a mixing agent for thelampblack or other soot, since it is diflicult to cause lampblack to mixwith water alone. This sugar solution is also preferably fermented tosome extent before the coating is applied to the sheets, so as toprovide some alcohol in the suspending medium. While an aqueous, alcoholsolutionmay be used, I 3 have found that commercial alcohol for thispurpose is expensive and that equally satisfactory results may beobtained by providing 90 the solution of the glucose or molasses andfermenting it either before or after admixture with the various forms ofcarbon.

As a specific example of a coatin mixture which embodies my invention oriscovery, the following sample mixture is given:

Lampblack 10 lbs. Graphite 10 Charcoal a- 20 Glucose; 2 Water 400 gal.

These materials are thoroughly mixed together and allowed to ferment tosome extent, the fermentation being accelerated, if desired, by theaddition of a ferment, such as yeast, to the mixture. If desired, theglucose and water may be added to the lampblack or other soot andthoroughly mixed therewith, and after the fermentation is thecharcoal,if charcoal is used. While the v ingredients of this composition mamlxed in any desired order, or the soli s all started the graphite maybe added and also added to the liquid at the same time and stirredtherein, I have found that somewhat better results are obtained if thegraphite is added after the fermentation has started. The mixture may beused for coatin purposes before the fermentation is complete or afterthe fermentation has stopped.

' I'have found that for the most satisfactory results, the lam black orother soot and the graphite shoul be used in approximately equalproportions, but the proportion of the charcoal may be varied through awider range andmay be used to some extent to replace the lampblack orother soot.

' ampblack or other soot may be entirely re- The placed by the finelydivided charcoal, if desired, but I have found that with little or nolampblaok and a major amount of charcoal it is not possible to obtain asglossy a finish as when more of the lampblack is used. If desired,-little or no charcoal may be used in "which case a larger proportion ofthe soot or 1am black may advantageously be used,

but sue a mixture is more expensive than when some charcoal is used.

After the mixture of different forms of finely divided, chemicallyuncombined carbon with the suspension medium has been made, the sheetsto be rolled are coated with this liquid mixtureand allowed to dry. The

sheets are then placed in packs, heated to,

the rollin temperature and then rolled, during which the sheets areenlarged in area and reduced in thickness. The coating may be applied tothe sheets in any suitable manner, such as by dipping the sheets intothe liquid mixtureor by spraying the mixture 11- on the sheets. Thecoating mixture may,

i desired, be heated so that the sheets coated therewith will dryrapidly, and the coatin" retained upon the sheets will remain fixedthereon while the sheets are being handled and matched up. The exposedfaces of the sheets of the packs, such as the tops, and but tom faces ofthe pack, mayalso be coated with the mixture in order to protect themunder the rolling pressure placed thereon during the rolling operation.

It is important that the various forms of carbon used be .in very' fineldivided condition in order that they will be more easily and uniformlyretained in suspension in the mixture and, consequently, more uniformlyspaced. upon the sheets. The finer the particles, the fewer theimperfections and indentations which will be formed on the surface oftherolled sheets and, therefore the hi her the uality of the sheets. Whie rap ite and c arcoal in a' water mixture could be used as a coatingmixture and would result in" sheets having some of the advantages of mydiscovery, a brighter and better sheet is obtained when the coatingmixture includes lampblack or other soot and the fine particles arecarried in suspension in the fermented solution.

In the heating operation, just prior to the rolling, the charcoal is thefirst to burnout and, when burned, leaves a slight ash which aids inkeeping the iron sheets from sticking to one another. The charcoalmixture .forming the coating also aids in keeping the lampblack or othersoot and the graphite particles separated or spread evenly, and thusreduces the cost-of the mixture since the powdered charcoal is lessexpensive than the soot or lamp black andthe gra hite. The

graphite is the best lubricant ween the sheets and will withstand hightrfurnace temperatures before burning. out, than will the lampblack orcharcoal, so that the sheets so coated may be heated to a much highertemperature in the furnace before'rolling than when lampblack and/orcharcoal alone is used. Consequently, the sheets at the highertemperatures ma be rolled more easily and perfectly and with fewerdefects because less force is required to elongate the material of thesheets at the higher temperatures.

Among the advantages resultin from the rocesses menuse of the improvedmixture an according to this invention, may

tioned the following. The improved coating resists the formation ofscale and oxides on the metal sheets during the heating, of the sheetspreparatory to rolling, prevents or lessens scratching of the sheets,and also the formation of the scale on the sheets in the anflashes anddiscoloration, will not sweat while placed in piles in the finishingdepartment, will not rust or undergo other changes due to atmosphericconditions during storage or shipment, even. though the sheets arecleaned of the coating before shipment, because dur-,

ing the rollingof sheets coated in this man-. ner, the surfaces of thesheets have been closed so thorou hly and such a highly glossy surfaceprodTzced, that it is impossible for water or moisture to get into thepores of the sheets and set u Sheets coated: before rolling, inaccordance with this invention, have such a, smooth,

a rusting or scaling action.

glossy, and closed grain surface that the cost of subsequent coldrolling to provide such a surface is largely saved. The lampblack orother soot and the charcoal maybe considered as a controlling agent forthe graphite, to prevent slipping of the graphite, or

displacement thereof. Since the sheets coated in accordance with thisinvention may be heated to a higher temperature for the rollingoperation, the sheetswill not be hardened by the rolling to the extentthat would occur under excessive cold rolling, and consequently havebetter drawing properties than sheets heretofore possible.

It will be obvious that various chan es in the proportions of parts ofthe ingre lents, in the order of the steps and in the other'details,which have been herein set forth in order to ex lain the nature of theinvention, may be ma e by those skilled in the art within the principleand sco e of the invention, as

- expressed in'the appen ed claims.

-I claim:

1'. A mixture for use in preventing adhesion between metal sheets duringpack rolling or the like, containing finely divided carbon in aplurality of different, chemically uncombined forms, one of .which isgraphite, and a fermented sugar solution.

2. A mixture for use in preventing adhesion between metal sheets durinpack rolling or the like, containing finely ivided carbon in a pluralityof different, chemically uncombined forms, one of which is graphite,

and a fermented glucose solution.

3. A mixturefor use in preventing adhesion between metal sheets duringpack rolling or the like, containing. finely divided graphite, finelydivided charcoal, soot, and a fermented, liquid suspension medium.

4. A mixture for use in preventing adhesion between metal sheets duringpack rolling, or the like, containing finely divided graphite, finelydivided charcoal, soot, and a fermented liquid suspension medium, mixedin the proportions approximately of 10 pounds each of graphite and soot,10 to 30 pounds of charcoal, and 400 gallons of liquid.

5. A mixture for use in preventing adhesion between metal sheets duringpack rolling or the like, containing finely divided carbon in aplurality of different, chemicall uncombined forms, and a'fermented,liqui suspending medium. I

' MERLE J. STOOPS.

